- C. Tarnocai et al (2009) – Soil organic carbon pools in the northern circumpolar permafrost region – Global Biogeochemical Cycles 3:GB2023 doi:10.1029/2008GB003327 – 27/06/2009 – Research Branch, Agriculture and Agri-Food Canada – 6 authors – Peer reviewed
“The Northern Circumpolar Soil Carbon Database was developed in order to determine carbon pools in soils of the northern circumpolar permafrost region. The area of all soils in the northern permafrost region is approximately 18,782 × 103 km2, or approximately 16% of the global soil area. In the northern permafrost region, organic soils (peatlands) and cryoturbated permafrost-affected mineral soils have the highest mean soil organic carbon contents (32.2–69.6 kg m−2) … Our estimate for the first meter of soil alone is about double that reported for this region in previous analyses … In total, the northern permafrost region contains approximately 1672 Pg of organic carbon, of which approximately 1466 Pg, or 88%, occurs in perennially frozen soils and deposits. This 1672 Pg of organic carbon would account for approximately 50% of the estimated global belowground organic carbon pool.” - Amanda Leigh Mascarelli (2009) – A sleeping giant? – Nature Reports Climate Change doi:10.1038/climate.2009.24 – 05/03/2009 – Freelance science writer based in Denver, Colorado –http://www.nature.com/climate/2009/0904/full/climate.2009.24.html– Peer reviewed
“For now, scientists are working quickly to answer pressing, yet basic questions, such as how much methane could be released as a result of warming, and when. «We first need sound science to use as a basis for understanding what the methane emissions are and how they may be changing right now,» says Ruppel. In the meantime, how concerned should we be about the possibility of climate catastrophe resulting from methane? «It’s probably safe to say that we don’t know,» says White. «But if there’s a ticking bomb in the room, you’d like to know the possibility of it going off. The fact that it’s there at all is unnerving.” - I. Eisenman and J. S. Wettlaufer (2009) – Nonlinear threshold behavior during the loss of Arctic sea ice – Proceedings of the National Academy PNAS 106:28-32 doi:10.1073/pnas.0806887106 – 06/01/2009 – Department of Earth and Planetary Sciences, Harvard University –Peer reviewed
“Our analysis suggests that a sea-ice bifurcation threshold (or “tipping point”) caused by the ice–albedo feedback is not expected to occur in the transition from current perennial sea ice conditions to a seasonally ice-free Arctic Ocean, but that a bifurcation threshold associated with the sudden loss of the remaining seasonal ice cover may occur in response to further heating … when sea ice covers the Arctic Ocean during fewer months of the year, the state of the Arctic becomes less stable and more susceptible to destabilization by the ice–albedo feedback. In a warming climate, as discussed above, this causes irreversible threshold behavior during the potential distant loss of winter ice, but not during the more imminent possible loss of summer (September) ice.” - Bruce Buffett and David Archer (2004) – Global inventory of methane clathrate: sensitivity to changes in the deep ocean – Earth and Planetary Science Letters 227:185-199 – 08/10/2004 – Department of Geophysical Sciences, The University of Chicago – Peer reviewed
“Our estimate of the methane inventory is sensitive to the efficiency of methane production from organic matter and to the rate of fluid flow within the sediment column. Preferred values for these parameters are taken from previous studies of both passive and active margins, yielding a global estimate of 31018 g of carbon (3000 Gton C) in clathrate and 21018 g (2000 Gton C) in methane bubbles. The predicted methane inventory decreases by 85% in response to 3 8C of warming. Conversely, the methane inventory increases by a factor of 2 if the O2 concentration of the deep ocean decreases by 40 AM or carbon rain increases by 50% (due to an increase in primary production).” - Kevin Shaefer et al (2011) – Amount and timing of permafrost carbon release in response to climate warming – Tellus B doi:10.1111/j.1600-0889.2011.00527.x – Published online: 15/02/2011 – National Snow and Ice Data Center, Cooperative Institute for Research in Environmental Sciences, University of Colorado – 4 authors – Peer reviewed
“By 2200, we predict a 29–59% decrease in permafrost area and a 53–97 cm increase in active layer thickness. By 2200, the PCF strength in terms of cumulative permafrost carbon flux to the atmosphere is 190 ± 64 Gt C. This estimate may be low because it does not account for amplified surface warming due to the PCF itself and excludes some discontinuous permafrost regions where SiBCASA did not simulate permafrost. We predict that the PCF will change the arctic from a carbon sink to a source after the mid-2020s and is strong enough to cancel 42–88% of the total global land sink. The thaw and decay of permafrost carbon is irreversible and accounting for the PCF will require larger reductions in fossil fuel emissions to reach a target atmospheric CO2 concentration.” - Joseph Romm – Are Scientists Overestimating – or Underestimating – Climate Change, Part I – Climate Progress – 28/03/2007 –http://climateprogress.org/2007/08/21/are-scientists-overestimating-or-underestimating-climate-change-part-i/
“Scientists have underestimated current climate change: ‘The recent [Arctic] sea-ice retreat is larger than in any of the (19) IPCC [climate] models’ – and that was a Norwegian expert in 2005. The retreat has accelerated in the past two years. The ice sheets appear to be shrinking ‘100 years ahead of schedule.’ That was Penn State climatologist Richard Alley in March 2006. In 2001, the IPCC thought that neither Greenland nor Antarctica would lose significant mass by 2100. They both already are. The temperature rise from 1990 to 2005 – 0.33°C – was ‘near the top end of the range’ of IPCC climate model predictions. Sea-level rise from 1993 and 2006 – 3.3 millimetres per year as measured by satellites – was higher than the IPCC climate models predicted. The subtropics are expanding faster than the models project. Since 2000, carbon dioxide emissions have grown faster than any IPCC model had projected.” - Vladimir E. Romanovsky et al (2001) – Permafrost Temperature Dynamics Along the East Siberian Transect and an Alaskan Transect (Extended Abstract) – Tôhoku Geophysical Journal 36:224-229 – Received: 08/11/2000 – Geophysical Institute , University of Alaska Fairbanks – 5 authors – Peer reviewed
“The results show that in general interannual and decadal variability in the air temperatures significantly increases «inertia» of permafrost to degradation. Cold «extreme events» refreeze the shallow taliks developed during the warm periods, and «recharge» permafrost with additional cold. For the scenario with a trend, after 2040 permafrost at the Fairbanks site shows continuous thawing. However, for the both Fairbanks and Yakutsk sites, the period from 2015 to 2025 (2020 to 2030 for Yakutsk) will see the beginning of permafrost instability and degradation. During these times, thermokarst processes may become very active affecting ecosystems and infrastructures in these regions … Disturbances related to forest fires significantly increase the probability of permafrost degradation in the near future. Our temperature measurements and calculations show that for most of the time after 1975, the mean annual ground surface temperatures at the Fairbanks sites were (and probably will be) above 0°C.” - David M. Lawrence and Andrew G. Slater (2005) – A projection of severe near-surface permafrost degradation during the 21st century – Geophysical Research Letters, 32, L24401, doi:10.1029/2005GL025080 – 17/12/2005 – Climate and Global Dynamics Division, National Center for Atmospheric Research – Peer reviewed
“The spatial extent of simulated present-day permafrost in CCSM3 agrees well with observational estimates – an area, excluding ice sheets, of 10.5 million km2. By 2100, as little as 1.0 million km2 of near-surface permafrost remains. Freshwater discharge to the Arctic Ocean rises by 28% over the same period, largely due to increases in precipitation that outpace increases in evaporation, with about 15% of the rise directly attributable to melting ground ice. Such large changes in permafrost may provoke feedbacks such as activation of the soil carbon pool and a northward expansion of shrubs and forests.” - Sergey A. Zimov et al (2006) – Permafrost and the Global Carbon Budget – Science 312:1612-1613 doi:10.1126/science.1128908 – 38884 – North-East Scientific Station, Pacific Institute for Geography, Russian Academy of Sciences – 3 authors – Peer reviewed
“Permafrost is a globally significant carbon reservoir that responds to climate change in a unique and very simple way: With warming, its spatial extent declines, causing rapid carbon loss; with cooling, the permafrost reservoir refills slowly, a dynamic that mirrors the past atmospheric record of CO2” - Edward A. G. Schuur et al (2009) – The effect of permafrost thaw on old carbon release and net carbon exchange from tundra – Nature 459:556-559 doi:10.1038/nature08031 – 28/05/2009 – Department of Biology, University of Florida, Gainesville – 6 authors – Peer reviewed
“Our data document significant losses of soil carbon with permafrost thaw that, over decadal timescales, overwhelms increased plant carbon uptake13–15 at rates that could make permafrost a large biospheric carbon source in a warmer world.” - Peter Kuhry et al (2010) – Potential remobilization of belowground permafrost carbon under future global warming – Permafrost and Periglacial Processes 21:208-214 doi:10.1002/ppp.684 – 08/06/2010 – Department of Physical Geography and Quaternary Geology, Stockholm University – 5 authors – Peer reviewed
“A new estimate of 1672 Pg C of belowground organic carbon in the northern circumpolar permafrost region more than doubles the previous value and highlights the potential role of permafrost carbon in the Earth System … The large permafrost carbon pool is not equally distributed across the landscape: peat deposits, cryoturbated soils and the loess-like deposits of the yedoma complex contain disproportionately large amounts of soil organic matter, often exhibiting a low degree of decomposition. Recent findings in Alaska and northern Sweden provide strong evidence that the deeper soil carbon in permafrost terrain is starting to be released, supporting previous reports from Siberia. The permafrost carbon pool is not yet fully integrated in climate and ecosystem models and an important objective should be to define typical pedons appropriate for model setups. The thawing permafrost carbon feedback needs to be included in model projections of future climate change.” - Jonathan A. Foley (2005) – Tipping Points in the Tundra – Science 310:627-628 doi:10.1126/science.1120104 – 28/10/2005 – Center for Sustainability and the Global Environment (SAGE), Nelson Institute for Environmental Studies, University of Wisconsin – Peer reviewed
“Chapin et al. provide the best empirical evidence for this climate feedback mechanism to date; these results need to be more fully incorporated into models of future climate change.” - Timothy M. Lenton et al (2008) – Tipping elements in the Earth’s climate system – Proceedings of the National Academy of Sciences PNAS 105:1786-1793 doi:10.1073/pnas.0705414105 – 12/02/2008 – School of Environmental Sciences, University of East Anglia, and Tyndall Centre for Climate Change Research – 7 authors – Peer reviewed
“We critically evaluate potential policy-relevant tipping elements in the climate system under anthropogenic forcing, drawing on the pertinent literature and a recent international workshop to compile a short list, and we assess where their tipping points lie. An expert elicitation is used to help rank their sensitivity to global warming and the uncertainty about the underlying physical mechanisms. Then we explain how, in principle, early warning systems could be established to detect the proximity of some tipping points.” - Matthew C. Hansen et al (2010) – Quantification of global gross forest cover loss – Proceedings of the National Academy of Sciences PNAS doi:10.1073/pnas.0912668107 – Published online: 26/04/2010- Geographic Information Science Center of Excellence, South Dakota State University – 3 authors – Peer reviewed
“GFCL [quantify gross forest cover loss] was estimated to be 1,011,000 km2 from 2000 to 2005, representing 3.1% (0.6% per year) of the year 2000 estimated total forest area of 32,688,000 km2… At national scales, Brazil experienced the largest area of GFCL over the study period, 165,000 km2, followed by Canada at 160,000 km2. Of the countries with >1,000,000 km2 of forest cover, the United States exhibited the greatest proportional GFCL and the Democratic Republic of Congo the least. Our results illustrate a pervasive global GFCL dynamic.” - Corinne Le Quéré, Michael R. Raupach, Josep G. Canadell, Gregg Marland et al (2009) – Trends in the sources and sinks of carbon dioxide – Nature Geoscience doi:10.1038/ngeo689 – Published online: 17/11/2009 – School of Environment Sciences, University of East Anglia – 24 authors – Peer reviewed
“In the past 50 years, the fraction of CO2 emissions that remains in the atmosphere each year has likely increased, from about 40% to 45%, and models suggest that this trend was caused by a decrease in the uptake of CO2 by the carbon sinks in response to climate change and variability. Changes in the CO2 sinks are highly uncertain, but they could have a significant influence on future atmospheric CO2 levels. It is therefore crucial to reduce the uncertainties.”
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